I want to throw my 2 cents in on this topic since I've been struggling with this problem for a month. I purchased the Samsung Frame TV right around Christmas '18. I experienced the audio dropouts right away when I connected the audio output to my Peachtree Nova 150 stereo receiver/amp.
Now, it's a bit of a complicated story here, but when I initially set up the TV, my Peachtree was in the shop, so I temporarily connected the TV to my Sonos amp. The sonos amp doesn't come with digital inputs, so I had to use a digital to analog coverter (DAC), which was a Chord Mojo portable DAC. I had no issues at all with this setup in regards to audio dropouts.
A few weeks into owning the TV, my Peachtree came back from the shop, and I disconnected the Sonos and used the Peachtree...and bam, audio dropouts constantly. The receiver was connected via optical, not HDMI, by the way. The TV setting was set to PCM output, since a stereo receiver cannot handle Dolby 5.1. I noticed that dropouts only happed during music. Dialog scenes from Netflix or youtube didn't have this problem. But if I played music on youtube, or when music played on a show in Netflix the dropouts would start again. Since this dropout problem was new to me after owning the TV for a few weeks, I reached out to the Peachtree service group, rather than Samsung. I did a bit of lurking online, but never called Samsung because the problem seemed to be associated with the receiver.
The Peachtree service department confirmed that they have seen this problem before, but more with LG TVs. Their explanation was that the built-in DAC in a high-end receiver needs a high quality audio signal. These TVs have digital audio components that are on the lower quality end (no surprise), and the jitter introduced by them caused problems with the sound processing on the receiver end. That service team had me try a few different things, such as getting an HDMI-ARC to optical converter box, to see if the HDMI signal output was better than the built-in optical output. This didn't really help. There was maybe a slight improvement, but nothing major.
I decided to try the DAC theory again, and used the built-in optical output to my Chord Mojo DAC, and then connected the analog output to the L/R inputs on the Peachtree receiver. No problems at all. The Mojo processed the signal just fine. The mojo isn't meant to be a stationary DAC (battery powered, etc), so I found a cheap ($12) DAC on Amazon that had optical input option, and stereo L/R analog output. My Peachtree is amplifying the output to my stereo speakers, but it isn't doing any of the digital signal processing. I am no longer experiencing any dropouts with this arrangement, so I consider this a permanent solution for me.
TL;DR: your audio receiver may have audio components that require a more precise digital signal to decode. The TV has a low quality digital signal that has too much jitter, which results in dropouts. The solution is to introduce a cheap DAC between the TV and receiver. Optical out from TV - cheap DAC - analog signal to your receiver. I only use a stereo speaker pair. If you are experiencing this problem with a surround speaker system, this solution is not for you since the DAC output is only L/R stereo. Maybe there is a cheap surround DAC that you can purchase?
